1. Field of the Invention
The present invention relates to a sheet-accommodating cassette used in an image forming apparatus, such as a copying machine or a printer, for accommodating sheets supplied to the image-forming apparatus.
2. Description of the Related Art
In recent years, the number of different sizes of sheets used in copying machines or printers has increased, enabling the user to use a variety of sheet sizes. Consequently, there has been an increasing demand for a sheet-accommodating cassette corresponding to sheets of various different sizes.
To satisfy this, there are sheet-accommodating cassettes corresponding to individual sheet sizes which the user can selectively purchase. However, this requires the manufacturer to manufacture and handle a variety of sheet-accommodating cassettes, decreasing its efficiency and increasing its production cost.
The user must selectively purchase various types of sheet-accommodating cassettes, which are costly and require a large space for storage. Therefore, this way of manufacturing and preparing sheet-accommodating cassettes corresponding to individual sheet sizes is not satisfactory for either the manufacturer or the user.
Hence, a universal cassette capable of accommodating sheets having various different sizes has been proposed. In a conventional universal cassette, a sheet end portion-restricting member (including a side-restricting member for restricting the side portion of a sheet and a rear end-restricting member for restricting the rear end of a sheet) is provided so as to be movable in the sheet-accommodating cassette. Each of the end portion-restricting members moves according to the size of the sheet used.
However, the above-described conventional universal cassette has the following problems.
In a conventional universal cassette, a sheet-accommodating cassette body (container) is designed to accommodate maximum sized sheets, and the movement of the end portion-restricting member provided in the cassette body enables the cassette body to accommodate sheets having smaller sizes. Thus, even when the maximum-sized sheets are not used, the large size sheet-accommodating cassette must be used. Such a cassette is not easy to handle in terms of its weight and size.
The large universal cassette is disadvantageous to both the manufacturer and the seller, due to increases in manufacturing and transportation costs.
Furthermore, there is a trend towards reduction in the size of the image-forming apparatus, such as a copying machine or a printer, and the size of sheets mainly used in image-forming apparatuses is thus A4 or letter size. Under such circumstances, the use of a large universal cassette designed for sheets of legal size, which is the maximum size, increases the effective area of the image-forming apparatus body required to install the apparatus body, impeding the reduction of the size of the apparatus and adversely affecting its design. Particularly, in a small desktop personal printer, the use of such a large sheet-accommodating cassette cannot satisfy the user's desire for reducing the size of the apparatus.